The subject matter disclosed herein relates to maintaining efficiency during the recovery of hydrocarbons from wellbores in earth formations. Efficient hydrocarbon recovery can be detrimentally affected by voids in gravel packs and collapses in open boreholes. Voids and collapses cause variations in flow rates, resulting in locally high flow rates that can erode sections of perforated production completion components, for example. Additionally, such locally high flow rates can cause debris to swirl and impinge upon walls of the production string and the borehole causing erosion and other damage thereto. Detecting and locating voids and collapses can allow an operator to alter production strategies to prevent such damage and is therefore desirable.